[85.06] Optical Spectroscopy of XRTE J1118+480

We report on optical spectra of XTE J1118+480, discovered by
RXTE on March 19 2000. Observations were taken with the MDM
2.4-m Hiltner telescope and CCDS covering the interval
3700-5400 Å\ at a spectral resolution of about 4 Å. The
spectra from April and May of 2000 reveal double-peaked
emission lines of HeII 4686. The blue and red peaks are
offset from the line center and are stationary with time.
The line profile changes over the course of the observations
and is asymmetric, with the blue peak ranging from being
equal to or stronger than the red peak. Measurments of the
equivalent widths of the peaks reveal that the blue peak EW
varies by a factor of 2 on a timescale which agrees with the
0.17d orbital period suggested by Patterson et. al (IAUC
7412). No systematic variation is seen in the red peak EW.